KNES 260 Physiology Final

what is an alternative name for the alimentary canal?

gastrointestinal or GI tract

What is the function of motilin??

Promotes motility in SI

When is prolactin released?

Mainly suckling

what structures make up the gastrointestinal or GI tract?

mouth, pharynx, esophagus, stomach, small intestine, large intestine

what are the accessory glands of the digestive system?

teeth, tongue, salivary glands, gallbladder, liver, pancreas

do the accessory glands see food?

no except for the teeth and tongue

what are the six essential digestive activities?

ingestion, propulsion, mechanical digestion, chemical digestion (involves secretion), absorption, defecation

What has the same general structures as the digestive tract?

esophagus and anus

what are the four major tissue layers of the digestive tract?

mucosa, submucosa, muscularis externa, serosa

what is mucosa?

inner most layer of digestive tract tissue, secretes mucous, important for absorption

What is submucosa? What does it contain?

contains blood and nerve supply

what is the muscularis externa important for?

motility

what is the serosa?

outer connective tissue layer

What does the myenteric plexus control?

muscle mobility

what does the submucous plexus control?

secretion of mucous, enzymes, and hormones

what are the different GI tract sensory receptors?

mechanoreceptors, chemoreceptors

what do mechanoreceptors respond to?

stretch as food moves through

what do chemoreceptors respond to?

osmolarity and pH changes, digestive substrates and end products (food)

How do chemoreceptors relate to digestive enzymes?

send out digestive enzymes needed by telling the organ what it needs to secrete

what are the general reflexes initiated by mechanoreceptors and chemoreceptors? What is the function of the initiated reflexes?

activate or inhibit digestive glands, stimulate smooth muscle to mix and move lumen contents

What are the two types of controls for GI tract sensory receptors?

extrinsic and intrinsic controls

what are extrinsic controls for the GI tract sensory receptors?

controls from outside the digestive tract

what are intrinsic controls for the GI tract sensory receptors?

controls from within the digestive tract

What do internal and external controls for GI tract sensory receptors affect?

motility, secretion of enzymes/hormones

what is an alternative name for intrinsic controls of the GI tract?

short reflexes

what is an alternative name for extrinsic controls of the GI tract?

long reflexes

what are short reflexes?

enteric nerve plexuses (gut brain) respond to stimuli in GI tract

what are long reflexes?

respond to stimuli inside or outside the GI tract, autnomic control/CNS

what are some examples of things that trigger your long reflexes?

thought or smell of food

what is the role of hormones in the extrinsic/intrinsic controls of the GI tract?

stimulate target cells in same or different organs

Where do enzymes come from in order to contribute to the extrinsic/intrinsic controls of the GI tract?

from stomach and small intestine

What are the four digestive processes?

motility, secretion, absorption, digestion

what is motility?

muscular contractions that mix and move forward the contents of the digestive tract

what are the two types of motility?

peristalsis and segmentation

What is peristalsis?

propulsive movements that move food based on slow waves potentials

What is segmentation?

mixing movements

what is the purpose of segmentation?

promotes digestion of foods, facilitates absorption

what hormones are involved in secretion in the digestive system?

CCK, gastrin, secretin

What do hormones involved in secretion effect in the digestive system?

motility and secretions

where do we find digestive enzymes?

mouth, stomach, small intestine

Where do we see mucous?

mouth, stomach, small intestine

what structures are important for absorption?

villi and microvilli

what is the function of villi and microvilli?

increase surface area for absorption

What is mechancial digestion?

digestion by chewing

What is chemical digestion?

chemical breakdown by enzymes of carbohydrates, proteins, fats

What are the types of carbohydrates?

starch, dissaccarides, monosaccarides, complex carbohydrates

what proportion of carbohydrates is accounted for by starch?

2/3

what are some examples of dissaccarides?

sucrose, lactose, maltose

what are examples of monosaccarides?

glucose

what are some examples of complex carbohydrates?

fibre, oligosaccarides

which type of carbohydrate is absorbed right away?

monosaccarides

what type of carbohydrate is an oligosaccaride?

complex carbohydrate

what enzymes breakdown carbohydrates?

amylase and SI enzymes (lactase, maltase)

where do amylase that breakdown carbohydrates come from?

salivary glands and pancreas

where do amylase from salivary glands act in?

mouth

where do amylase from pancreas act in?

small intestine

where do lactase and maltase come from and what do they act in?

from SI wall, acts in SI

explain the path of starch digestion?

starch convert to maltose using amylase in the mouth and SI, maltase breaks down maltose into glucose in the SI, glucose absorbed directly in the blood

Can humans directly digest complex carbohydrates?

no, humans lack enzyme to digest complex carbohydrates

what enzyme is used to digest complex carbohydrates?

alpha galactosidase

how do we digest complex carbohydrates?

fibre moves to LI for e coli digestion, fermentation occurs then gas produces

about how much protein do we need per day?

50-60g

what are proteins made of?

essential amino acids

what enzymes are secreted for protein digestion?

pepsin, trypsin/chymotrypsin, carboxypepsidase, aminopeptidase, dipeptidases

where is pepsin secreted from for protein digestion?

stomach

which organ secretes multiple enzymes for protein digestion?

pancreas

Where do enzymes working on protein digestion act in?

small intestine

Why are many enzymes needed for protein digestion?

needed to break the bonds between the different amino acids

where is alastase secreted from?

stomach

where does alastase act in?

small intestine

what does alastase break down?

connective tissue

what does pepsin break down?

protein

what does trpysin/chymotrypsin break down?

protein

what does carboxypepsidase, aminopeptidase, and dipeptidase break down?

protein

what does amylase break down?

carbohydrates

explain the pathway of protein digestion

proteins are broken down by pepsin, trypsin/chymotrypsin in SI to polypeptides which are broken down into dipeptides by carboxypepsidase and aminopepsidase in SI, then into amino acids abosorbed directly into blood

are fats polar or non-polar?

non-polar

what is needed to break down fats?

emulsifier

is bile an enzyme?

no

where is bile made?

liver

where is bile stored?

gall bladder

what is the function of bile in digestion?

increases surface area of lipase

what enzyme is used in fat digestion?

lipase

where is lipase secreted from?

pancreas

where does lipase act in?

small intestine

explain the pathway of fat digestion

fat is broken down into smaller fat globules by bile in the SI, break down into glycerol and fatty acids by lipase in the SI, glycerol directly into blood and fatty acids go into lymph then blood

what does lipase act on?

emulsified droplets

Explain fat absorption

lipase acts on emulsified droplets, get monoglyceride and fatty acids, enter absorptive cells or form micells, form chylomicron within cell then absorbed into lymph

through which process does fatty acid move into lymph?

fat absorption

list the breakdown of fat in fat absorption

big droplets of fat to small droplets, micelles, fatty acids and monoglycerides, chylomicron assembly, distribution and processing

what are nucleic acids broken down by?

nucleases

what organ secretes nucleases?

pancreas

where do nucleases act?

small intestine

what enzymes along with nucleases aid in the breakdown of nucleic acids?

SI enzymes

what are vitamins absorbed by?

absorbed whole by carriers

what important part of digestion occurs in the mouth?

chewing, mechanical digestion

what occurs in the process of chewing? What is the purpose?

increase surface area and decrease choking

what is secreted during chewing in the mouth?

mucous and salivary amylase